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Tin oxide (SnO2) is an interesting material having novel structural and optical properties. To investigate the above properties, the sol-gel route is selected to prepare SnO2 nanoparticles. Detailed investigation of the structure such as; phase analysis and crystallinity was accomplished by the X-ray diffraction (XRD) method. It has been observed that the as-synthesized tin oxide has a tetragonal rutile structure. The synthesized SnO2 samples have an average crystallite size from 20 nm to 26 nm as ascertained from the XRD study. Morphology study by field emission scanning electron microscopy (FESEM) shows the evolution of monodispersed nanocrystallites of SnO2. The photocatalytic property of SnO2 nanoparticles was studied in degrading a cationic dye such as; methylene blue with the application of UV-Vis light. The dye degradation rate before & after illumination of UV-Visible light at (λ = 664 nm) was calculated which follows pseudo-first-order kinetics. The parameters such as catalyst dosage and pH have influences on the degradation rate which has been studied systematically. A degradation of 84.23 % has been obtained by tin oxide nanoparticles after 120 min of UV irradiation. This will eventually help in treating the industrial wastes mixed with water bodies targeting water pollution.

Nanocomposites of ZnO-SnO2 doped with Eu ions were synthesized by sol-gel method. The samples show the co-existence of hexagonal ZnO and tetragonal SnO2 crystallographic phases as observed from X-ray diffractometry studies. Eu doping facilitates the grain growth as the average grain size is found to increase with the increase in Eu dopant concentration. Surface morphology is also altered with Eu doping with energy-dispersive X-ray analysis measurement confirming existence of elements like Zn/Sn/Eu. Fourier transform infrared spectroscopy specifies the appearance of peaks linked with functional groups like Zn-O, Sn-O, and O-H. Photoluminescence study shows the evolution of characteristic emissions of Eu ions (5D0→ 7F1, 5D0→ 7F2, and 5D0→ 7F3). Photodegradation of toxic environmental dyes like Congo red and methylene blue was executed and the efficiency of degradation was estimated under visible light illumination. The presence of Eu3+ ions in ZnO/SnO2 helps to enhance the degradation efficiency by facilitating to form Z- scheme heterojunctions between ZnO and SnO2. This allows the delay in recombination rate of the photoinduced electron/hole pairs. The antibacterial behavior of the prepared nanocomposites against E. coli and S. aureus has also been studied in detail which demonstrates improved antibacterial efficiency of the samples.